Our study is directed towards the identification of the molecules in the membrane, involved in the interaction with sugar during absorption. During the last year we have been able to synthesize a radioactivity labeled photoaffinity probe. Having prepared a radioactivity labeled photoaffinity probe we plan: (a) To characterize its specificity and other properties both in the dark and after light activation. (b) We plan then to proceed to fractionate labeled proteins by use of column chromatography, HPLC, and SDS electrophoresis. (c) We also plan to attempt to isolate the unlabeled protein to be used in reconstitution experiments by using the probe as an assay system for the binding protein. (d) Finally we would like to use the probe as a meaning device to determine the number of carrier sites under a variety of physiological and pathological conditions.